An Alternative Method for the Invariant Threshold Force Evaluation in Incremental Step Loading Tests

2020 ◽  
Vol 49 (1) ◽  
pp. 20190568
Author(s):  
Danilo Eduardo Fonseca Souza ◽  
José Eduardo Silveira Leal ◽  
Waldek Wladimir Bose Filho ◽  
Rosenda Valdés Arencibia ◽  
Sinésio Domingues Franco
Keyword(s):  
Threshold Force ◽  
Alternative Method ◽  
Loading Tests ◽  
Step Loading ◽  
Incremental Step

scholarly journals Hydrogen Absorption during Case Hardening of Steels EN20MnCr5 (SAE5120) and EN18CrNiMo7-6 (SAE4820)

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 6
Author(s):  
Matthias Castens ◽  
Stefanie Hoja ◽  
Holger Surm ◽  
Franz Hoffmann ◽  
Rainer Fechte-Heinen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Embrittlement ◽  
Hydrogen Content ◽  
Fracture Pattern ◽  
Case Hardening ◽  
Loading Test ◽  
Step Loading ◽  
Incremental Step ◽  
Specific Fracture ◽  
Hardened Condition

Damages to case-hardened components are often associated with the phenomenon of hydrogen embrittlement due to their specific fracture pattern. In the present work, the effects of the case hardening process on the hydrogen content in the material were investigated and the effects of hydrogen on the mechanical properties were examined. In order to determine not only the influence of the heat treatment process but also the influence of the material, the case-hardening steels EN20MnCr5 (SAE5120) and EN18CrNiMo7-6 (SAE4820) with different degrees of purity were investigated. From the results it can be deduced that the sulphidic and oxidic inclusions have no significant influence on the hydrogen content. When checking the mechanical properties, it was shown in the incremental step loading technique according to ASTM F1624 that a purely case-hardened condition only has a slight tendency to hydrogen embrittlement. However, if the material is additionally loaded with hydrogen, the material fails significantly below the maximum expected load in the incremental step loading test, which is to be interpreted as a clear indication of failure due to hydrogen embrittlement. However, the fracture patterns of these two states do not show any significant differences. Therefore, it does not seem possible to attribute damage to a case-hardened component to hydrogen embrittlement on the basis of the fracture pattern alone.

Validation of the Incremental Step Loading Technique Application to Small Punch Tests in Aggressive Environments in X80 Steel

2020 ◽  
Author(s):  
B. Arroyo ◽  
L. Andrea ◽  
P. González ◽  
J. A. Álvarez ◽  
S. Cicero ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Embrittlement ◽  
Threshold Stress ◽  
High Strength ◽  
Constant Load ◽  
Small Punch Test ◽  
Small Punch ◽  
Punch Test ◽  
Step Loading ◽  
Incremental Step

Abstract The Small punch test, which consists on punching a small plane specimen up to failure, is a technique to be taken into account for the estimation of mechanical properties when there is shortage of material. In recent works it has been applied to the estimation of mechanical properties steels in aggressive environments. In aggressive environments, tests under a constant load are usually employed for the threshold stress determination, but this a slow and sometimes inaccurate technique. The standard ASTM F1624 solves these issues; it consists on applying steps of constant loads subsequently increased up to the specimen’s failure. In a previous work, it was indicated how to implement this technique for Small Punch testing of steels in hydrogen embrittlement scenarios, adapting the steps duration. This proposal allows to obtain a threshold load by using at least 3 specimens in a total time of around a week. In the present work, the incremental step loading technique from ASTM F1624 standard is applied to the Small Punch test in order to estimate tensile threshold stress of a X80 high strength steel in hydrogen embrittlement environments by cathodic polarization in an acid electrolyte. Regular standard tests on cylindrical tensile specimens were carried out following the ASTM F1624 standard, in order to validate the methodology proposed.

scholarly journals Stress-Strain Response Determination during Incremental Step Tests and Variable Loadings on Flat Specimens

Technologies ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 53 ◽  
Author(s):  
Domen Šeruga ◽  
Marko Nagode ◽  
Jernej Klemenc
Keyword(s):  
Strain Response ◽  
Variable Loading ◽  
Stress Strain ◽  
Damage Prediction ◽  
Stress Signal ◽  
Loading Tests ◽  
Sufficient Magnitude ◽  
Response Determination ◽  
Incremental Step ◽  
Initial Cracks

For stress-strain response simulations and damage prediction of cyclically loaded mechanical components, it is crucial to determine both the stress-strain and durability curves of the materials sued. Round and flat specimens can be used for this purpose, either following standard recommendations for their geometry or by designing a special geometry which enables special requirements, such as initial cracks of various shapes, attachment of an extensometer, special grips for raised temperatures, and so on. However, especially in the case of flat specimens having a slender shape, buckling can occur before the stress or strain values reach a sufficient magnitude in compression. To avoid this, an anti-buckling support can be attached to the specimen, which prevents the occurrence of buckling. In turn, friction occurs between the specimen and the anti-buckling support, which affects the measurement of the stress. If a special sensor is attached under the anti-buckling support, the friction force can be measured and subtracted from the stress signal, leaving only the stress-strain response of the material under investigation. In this study, two materials were investigated during incremental step and variable loading tests: The aluminium alloy AlMgSi0.5 and a biodegradable polylactide.

Traceability for measurements carried out on incremental step loading equipment

2019 ◽  
Vol 41 (8) ◽  
Author(s):  
Marcus Vinícius Rezende Júnior ◽  
José Eduardo Silveira Leal ◽  
Raphael Rezende Pires ◽  
Marcelo Torres Piza Paes ◽  
Francisco Francelino Ramos Neto ◽  
...  
Keyword(s):  
Step Loading ◽  
Incremental Step
Sign in / Sign up

Export Citation Format

Share Document